Rigid Unit Modes in $sp$-$s{p}^2$ Hybridized Carbon Systems: Origin of Negative Thermal Expansion

Cheol-Woon Kim, Seoung-Hun Kang, Young-Kyun Kwon

Using density functional theory combined with quasi-harmonic approximation, we investigate the thermal expansion behaviors of three different types (α, β, and γ) of graphyne which…